Hydraulic jack pumping plant



Aug. 4, 1942. J. A. VERTSON HYDRAULIC JACK PUMPING PLANT Filed June 16,1939 5 Sheets-Sheet l [nae/liar. -/0/zn ,9- Verlis'on.

Aug. 4, 1942. J. A. VERTSON HYDRAULIC JACK PUMPING PLANT Filed June 16,1939 5 Sheets-Sheet 3 /23 M2 /Z/a 2 flil'orm zy.

lflvenlor. 07222.14. Verlas'on.

Aug. 4, 1942. J. A. VERTSON I HYDRAULIC JACK PUMPING PLANT Filed June1.6, 1939 5 Sheets-Sheet 4 5 MW 7 a m m 3 3 0v m; n 2

1942- J. A. VERTSON 2,292,331

HYDRAULIC JACK PUMPING PLANT Filed June 16, 1959 5 Sheets-Sheet 5 I ll;

flilornery.

John J4. risen.

Patented Aug. 4, 1942 UNITED STATES PATENT OFFICE" HYDRAULIC JACKPUMPING PLANT John A. Vertson, Brca, Calit, assignor to Vertson RoyerCorporation, B

of Nevada rea, Calif., a corporation Application June 16, 1939, SerialNo. 279,396

7 Claims.

This invention relates generally to .deep well pumping plants, and moreparticularly to deep well pumping plants-of the hydraulic jack type.

valveproblem set forth, an hydraulic jack having a mastervalve forreversing the direction of flow between tank and cylinder, and a pilotvalve con- Hydraulic jack pumping plants of the class here referred tocomprise an accumulator containing a liquid under pressure, a workingcyl-.

inder and piston for reciprocating the pump rod string, and a pump andvalve system for alternately pumping working liquid from the accumu-'lator to the cylinder to elevate the piston and rod string, and thenfrom the cylinder to the accumulator to allow the piston and rod stringto trolling a pressure fluid for operating the master valve, this pilotvalve being mechanically operated by a linkage which is actuated, inturn, by

the working piston. There is suiiicient delay in the operation of themaster valve by the pressure fluid that the working piston is notbrought to a stop until after the pilot valve is thrown completely toflow-reversing position, and there is descend. By-maintaining a pressurein the accumulator equal to the pressure necessary in the workingcylinder to counterbalance the weight of the pump rod string plus onehalf the weight of therefore positive assurance that the valves will notstop on "dead center."

Alurther object oi the invention is the provision of an hydraulic jackwhich is so designed that the rates of deceleration and acceleration ofthe column of liquid carried by the rod string on A further and morespecific object of the invention is the provision of an hydraulicjackhaving a reversible flow circulating pump and valve system ofincreased simplicity as well as improved effectiveness. y

Prior pumping plants of the hydraulic jack type have usually employed aflow reversing valve operated mechanically by a linkage driven ortripped by the working piston. However, a simple mechanical linkagewillmove the valve only to a dead center position at which flow betweenthe tank and working cylinder ceases, since at this time the workingpiston ceases its motion and the linkage does not throw the valve onpast dead center to now reversing position. For this reason, a purelymechanical linkage must include some additional means for throwing thevalve on past dead center. Mechanisms for accomplishing this result havebeen provided in the past, but have invariably been either quitecomplicated or else unsatisfactory in performance.

An object of the present invention is the provision of a simple valvesystem which will avoid the dead center difficulties mentionedimmediately above. a 1 v The inventio provides as a solution to the theworkingpiston at the end of each stroke may be readily adjusted withincomparatively wide This. provision enables timing" of the accelerationand deceleration of the working piston to the natural and characteristicbehavior of the pump string, so that, for example, at the termination ofthe down stroke, the pump string is arrested in motion and thenpicked-up again in consonance with its natural resilient rebound.

As is well known, if the rate of deceleration and acceleration at thebottom of the stroke are not well matched to the natural resilientstretch and contraction characteristics of the pump string, whipping,jerkiness and loss of power, as well as undue strain on the string, areexperienced.

The provisions contemplated also enable adjustment of therates ofdeceleration and acceleration at the upper end of the stroke, it beingan important advantage to have available a means for adjusting theserates to most advantageous values for any given pumping speed. Thus, asindicated above, it is one primary purpose of the present invention toprovide means whereby the deceleration and acceleration of the workingpiston may be adjusted to values best suited to the characteristics ofthe pump rod string to which the pumping plant has been applied.

In accordance with the present invention, the rates of deceleration andacceleration of the working piston are adjusted by regulating the speedof travel of the master valve, which is in turn adjusted by regulationof the rate of flow of the high pressure fluid that operates the masterThis regulation is accomplished, in a A still further object of theinvention is the provision of a valve and pump system for an hydraulicjack characterized by elimination of the usual water hammer duringreversal of the valves.

In accordance with the invention, the master valve is so designed thatwhile moving to reverse the direction of flow between the accumulator'and working cylinder, the accumulator and working cylinder are placed indirect communication with one another through the chambers of the valve,so that the working piston is cushioned at such time by the air pressurein the accumulator, rather than coming to a jarring stop as the valvesclose off flow to the cylinder.

A feature of the invention is a novel type of action of the pump andvalve system during reversal of the direction of flow between tank andcylinder. As the master valve moves to reverse the direction of flow, itgradually decreases the flow between tank and cylinder, and at the sametime, a local ring circulation from the pump through the valve chamberand back to the pump is established. This local ring circulation throughthe valve increases until the entire output of the pump is diverted inthis manner and no liquid is pumped toward or from either the cylinderor tank. Further travel of the master valve then causes liquid to bediverted from this local ring circulation through the valve and to bedelivered to the tank, and at the same time causes the pump to begin totake liquid from the cylinder. The master valve thus decreases the localring circulation to zero, while increasing the circulation between thecylinder and pump to a maximum in a direction contrary to its initialdirection of flow. There is transition from maximum flow in onedirection to maximum flow in the other without closing off communicationbetween tank and cylinder, the pump circulating liquid locally throughthe valve during the transition, and all of the liquid discharged by thepump taking part in this local ring circulation through the valve atthetime flow between tank and cylinder momentarily ceases preparatory toreversing its direction.

Further objects of the invention relate to features of the workingcylinder, and to the flow connections and valves employed in connectionwith the pipe lines interconnecting. the several units of the plant.

With this preliminary discussion in mind, the invention itself, as wellas various additional object and features not specifically mentioned,will be made clear from the following detailed description of a presentpreferred embodiment of the invention, reference for this purpose beingdirected to the accompanying drawings, in which:

Fig. l is a side elevation, with parts broken away, of an illustrativehydraulic pumping plant in accordance with the present invention;

Fig. 2 is a vertical section through the gear pump and main valve chesttaken as indicated by line 2-2 of Fig. 1;

Fig. 3 is a vertical section through the pilot valve chest taken asindicated by line 3-3 of Fig. 2;

Fig. 4 is a vertical section taken as indicated by line 4-4 of Fig. 2;

Fig. 5 is a vertical section taken as indicated by line 5-5 of Fig. 2;

Fig. 6 is a section taken on broken line 66 of Fig. 2;

Fig. 7 is a section taken as indicated by line 1-7 of Fig. 2;

Fig. 8 is a section taken as indicated by line 8-8 of Figs. 1 and 2;

Fig. 9 is a vertical section through the working cylinder and pistontaken as indicated by line 9--6 of Fig. 1;

Fig. 9a is a detail section taken on line -901 of Fig. 9;

Fig. 9b i a detail section taken on line 9b-9b of Fig, 9;

Fig. 9c is a downward continuation of Fig. 9;

Fig. 10 is a view of the main pressure tank as seen from the rear inFig. l; and

Fig. 11 is a view taken on line ll|l of Fig. 10.

With reference now to the drawings, and particularly to Fig. 1, numerall5 designates generally a pressure tank or accumulator, numeral I6 theworking cylinder, and numeral i! a pump and valve unit for pumpingworking fluid alternately from tank I5 to cylinder l6 and then fromcylinder I 6 to tank I5. These units are indicated as mounted on orabove a suitable platform or flooring, indicated at 18, unit I! and thetank being indicated as furnished with a common base lBa resting onplatform l8. Accumulator I5 is shown provided with a bracket IS on whichis mounted an air compressor of any suitable type, generally designatedat 20, and indicated in Fig. l as driven by means of a belt 2| from anysuitable source of power, as an electric motor, not shown.

I prefer to employ a single vertically disposed working cylinderpositioned over and in alinement with the well casing, and the inventionis so illustrated, though without implied limitation thereto. Thus, ashere shown, working cylinder I6 is positioned over and in alinement withthe upper end of well casing C, only a fragmentary upper end portion ofthe latter appearing in the drawings. The polish rod is designated .bynumeral 22, and extends upwardly through cylinder 16 as clearlyillustrated in Fig. 9.

While the working cylinder and piston may be of any desired orappropriate construction, that here shown presents certain novelfeatures of advantage and will therefore be described in some detail.The illustrated cylinder l6 embodies a barrel 25, mounted at its lowerend on a lower cylinder head fitting 26, and having mounted on its upperend a cylinder head 21. The preferred mounting for barrel I6 on fitting26 consists of a ring 28 screw threaded on the lower end of barrel l6and secured to the upper end of fitting 26 as by means of screws 29. Ina similar manher, head 27 is preferably mounted on the upper end ofbarrel 25 by means of a ring 30 screwthreaded on the upper end of thelatter and secured to head 2'! by screws 3|. Fitting 26 has at thebottom a reduced rounded portion 32 received within the upper end of adepending tube or sleeve 33, fitting 26 and the parts above beingsupported by the engagement of the upper end of sleeve 33 with shoulder34. Screws 35, threaded in the upper end of sleeve 33 and engaging in aperipheral groove 36 formed around the lower end 32 of fitting 26,secure mcmbers 26 and 33 in assembly. Sleeve 33 is mounted in anysuitable manner on the usual tubing head 37 on the upper end of the wellcasing C (see Fig. 9c), the'tubing head being provided with a packinggland 38 for the polish rod, and having connected thereto a pipe line 39for receiving the well fluid.

The present preferred piston 40 for cylinder able packing means is ismade up of an upper head 4|, a lower head 2, and concentric outer andinner sleeves 43 nd 44 joining-with and extending between heads I and42. Sleeve 43 is internally threaded at ;s upper and lower ends forconnection at 45 nd 46 with external threads on heads 4| and 42,espectively. Inside sleeve 44, which is preferably d an inside diameterslightly greater than that if polish rod 22, so as to leave an annularclear- LHCB therebetween, is externally threaded at its lpper and lowerends, being screwed at its upper :nd within a screwthreaded socket 41formed in ;he underside of head 4!, and being screwed at .ts lower endinside internally threaded central Jore 48 of lower head 42. Cylinderhead 21 is formedv'ith a finished cylinder bore 50, within which outsidesleeve 43 of piston 40 has a working fit, bore 50 being of a the insidediameter of cylinder 25, so as to leave an annular clearance spacebetween cylinder 25 and the outside sleeve 43 of the piston. The lowerend of the piston is guided inside cylinder 25 by means of a notched orinterrupted fiange 5| projecting outwardly from lower piston head 42(see Fig. So), this interrupted flange having a comparatively freesliding fit inside cylinder 25.

The upper end of cylinder head 21 has a countersink 55, in which isreceived a U-leather packing ring 5'6, the latter being spread by asplit-resilient ring 51 of any suitable type. A cover 58 mounted on theupper end of cylinder head 21 has an annular downwardly projectingportion 59 received within countersink 55 and following up andsupporting U-leather 56. Cover 58, which is secured to the upper end ofcylinder head 21 as by screws 60, has a bore GI slidably embracingpiston 40, and is shown as provided with a wiper ring at 62. Cylinderhead bore 50 may be provided with suitable oil grooves, as indicated at53. The described construction provides for an exceptionally long strokeof the piston without necessitating an unduly long finished cylinderbore, the latter being only a fraction of the full length of cylinderl6.

Fitting 26 has a chamber opening through its upper side to the interiorof cylinder l6, and connected to this fitting and communicating withsaid chamber 10 and therefore with the interior of cylinder I6 is a pipe1| which leads from the driving pump. The lower portion of fitting 28 isbored to pass polish rod 22,-and suitprovided between the polish rod andthe lower portion of fitting 26, as indicated. For example, the fittingmay be provided with a packing gland 12, set up by a bushing 13screwthreaded into the lower end portion of the fitting. Access tobushing 13 and this packing is had by way of aperture 14 in sleeve 33Upper cylinder head 4| is bored to pass the upper end portion of polishrod 22, and to provide for a packing gland 41a which packs between thepolish rod and cylinder head. This packing gland is tightened by meansof a bushing 49 screwed into the upper end of head 4|. A rod clamp 49aon the upper end of the polish rod engages the upper end of bushing 49,and thus suspends the polish rod and pump rod string from working piston40.

A further feature of the invention illustrated in part by Fig. 9 is ameans for collecting oil which passes U-leather 56 and delivering itback to tank l5. Any such oil passes upwardly between the verticalsurfaces between the annular 58 and of countersink 55 to This oilthenportion 59 of cover an annular collection space 15.

diameter somewhat less than 7 drains by way of downwardly and outwardlyin-v clined passageway 16 to a pipe line 14, which leads to a drip tankas later to be described.

A pipe connected to pump and valve unit l1 leads via valve 8| to afitting 82 coupled to accumulator l5. The coupling employed preferablyemploys packing in such a way as to avoid direct metal to metal contactbetween coupling member 82 and the tank, so as to avoid transmission ofvibrations from the pump to the tank, which sometimes cause the tank toprovide noise. In the arrangement illustrated, fitting 82 is receivedwithin a packing ring or sleeve 83, which is mounted inside a tubing 84extending through and welded in the side wall of the tank. Pipe fitting85 is received and supported within packing sleeve 83, and projectsinwardly across the interior of the tank. This fitting B5 is providedwith a suitable liquid opening, as for instance the downwardly directedslots 85. Packing sleeve 83 may be tightened by any suitable means, asfor example by the follower and tightening device illustrated at 81.

The pumping plant of the present invention includes, in addition to mainpressure tank 15, a high pressure fluid source which preferablycomprises a smaller high pressure tank 86, and this small tankisconveniently and preferably mounted inside main tank l5. This highpressure tank 88 has connected thereto a. pipe line 89, which will beunderstood to extend through the wall of tank l5 and to communicate withthe interior of tank 88.

The discharge line from compressor 20 is designated by numeral 90 (seeFig. 11, in which the compressor itself, however, has been omitted).Compressor line 90 is connected to a pipe line 91 that connects to theaforementioned high pressure line 89 communicating with the interior ofhigh pressure tank 88, and this line 9| contains a check valve 92adapted to hold the pressure in high pressure tank 88. Compressor line90 also connects via valve with a fitting 96 that communicates by way ofvalve 91 with the interior of main tank l5. Check valve permits flow ofair from compressor 2D to tank l5, but holds the pressure in the tankwhen the compressor is stopped.

The previously mentioned oil line 14 that collects oil leaking past thepacking in cylinder head 21 is coupled to the bottom connection offitting 96, this line 14 having, just below fitting 96, a check valve 98preventing back flow in line 14. Assuming the pumping plant to be innormal running condition, valves 94 and 91 will be closed, and the oilcollected from cylinder head 21 will flow by way of line 14 into fitting96, thence upwardly through its upper connection and via valve 99 todrip tank H30. which latter is thus positioned above the valve 91 whichcommunicates with the interior of tank 15. Drip tank I00 has near itsupper end an oil inlet fitting IBI, provided with a closure plug I02.This closure plug N12 is provided with a pet-cock [03, which normallystands open and permits tank I00 gradually to fill from line 14 leadingfrom the working cylinder, as before described. The accumulation of oilin tank IE0 is from time to time discharged into main tank l5. This isaccomplished by first closing pet-cock I03 and then opening valve 91.This causes the pressures in main tank l5 and tank 100 to becomeequalized, whereupon the oil in tank will drain into tank l5. Valve 91is then closed and pet-cock 94 and check valve 95 oil is introduced tosupply the operating needs of the system; typically, tank I5 is aboutonefourth full of oil when the pumping plant is in normal operation. Tobuild up the air pressure in tank I5, valve 99 is closed and valves 94and 91 opened. Compressor 20 is then operated until the necessarypressure has been built up in tank I5, as read from pressure gauge I05.This pressure, as explained elsewhere, is substantially that which isnecessary in the working cylinder to counterbalance the weight of thepiston and pump rod string, plus one-half the weight of the column ofwell fluid, and may be designated as where R is the pressure necessaryto counterbalance the pump rod string, and

is the pressure necessary to counterbalance onehalf the weight of thecolumn of well fluid. In practice, it is usually desirable to initiallyovercharge the tank somewhat, that is, to a pressure somewhat above soas to allow for the certain inevitable gradual loss of pressure withoutimmediately falling below an operating minimum. The compressor at thesame time pumps air through connection 9| to high pressure line 89leading to high pressure tank 88. When the proper pressure is reached inmain tank I5, valve 94 is closed, check valves 95 and 98 holding thepressure in main I5, while the compressor continues to increase thepressure in high pressure tank 88. When a pressure of say 50 lbs.greater than the pressure in tank I5 is reached in tank 88, as read bygauge I06 connected into line SI, the compressor is stopped, the highpressure in tank 88 being held by check valve 92 (Fig. 10).

Preferably, and as a feature of the invention,

the driving pump and valves are embodied in a single unit II. This unitembodies a main cast ing IIO serving as a housing for the rotors orgears III and N2 of the pump proper, designated at P, and providing achest II4 for master valve II5. While the pump proper may be of anydesired Or appropriate type, I prefer to employ a gear pump of the typeembodying a pair of rotors formed with intermeshing double helical gearteeth II6, a pump of this type being particularly efllcient andfurnishing a constant, positive pressure. Rotors III and H2 have axles Iand I2I, respectively, journaled in suitable bearings I2Ia supported byend castings I22, the latter fitting closely around said axles adjacentthe rotor ends and presenting walls I23 defining the sides of the rotorchamber. A pump drive shaft I20a carrying a driving pulley I201) extendsfrom one of the axles I20 (Figs. 1 and 8). A cover plate I25 closes oneof the bearing supporting castings I22, while the other bearingsupporting casting I22 carries a closure member I26 furnished with apacking gland I2"! for drive shaft I20a.

Casting IIO includes two substantially semicircular walls I30 and I3Ifitting closely around the outer sides of rotors III and I I2, thesewalls joining at their edges with horizontally spaced vertical wallsI32. A peripheral wall I33 joining with walls I32 forms the outer sidesand top of the pump casing, and, together with walls I32, merges withthe top of valve chest I I4.

The aforementioned master valve II5 may be embodied in variousmechanical forms, though it is preferably a balanced, linearlytravelling valve. This valve H5 is mounted for reciprocation in a valvebore I in valve chest II4, said bore extendingv transversely of the axesof pump rotors III and H2, in the disposition clearly shown in Fig. 2.Valve bore I40 opens through opposite ends of valve chest H4, andcommunicates with certain later described ports or passages formed inend castings MI and I42 secured to opposite ends of valve chest I I4.

Master valve II5, in the present preferred and this port being of adimension, measured axially of the valve bore, equal to twice thethickness of valve disk I53. Port I communicates with a pump intakechamber I6I leading directly to the lower side of pump rotors III andH2, via the port defined by the lower ends of semi-circular walls I30and I3, this intake chamber I 6 I being enclosed by the aforementionedwalls I32 of the main casting and by walls I62 joining with andextending downwardly from walls I 30 and I3I, as clearly shown in Fig.2. Thus the intake side of the pump is at all times in opencommunication with port I60, and, the pump rotors being understood to bedriven in the directions indicated by the arrows in Fig. 2, it will beunderstood that suction will be developed in chamber IBI drawing liquidfrom port I60 upwardly through chamber I6I, thence around the inside ofwalls I30 and I3I within the spaces between gear teeth II6, to bedischarged to the two pump discharge passageways I63 and I64 via theport defined by the upper ends of walls I30 and I3I, the oil travellingin the paths indicated by the arrows in Fig. 2. It should be pointed outthat while one direction of operation for the pump is here assumed, thisis not at all limitative, since the system will operate with the pumprotors running in either direction.

On opposite sides of port I60 are valve seats I65 and I66 for valve diskI53, these seats each being of a width substantially equal to thethickness of valve disk I53. Surrounding valve bore I40 outside valveseats I65 and I66 are annular ports or valve chambers I61 and I68, ofdimensions, measured axially of valv bore I40, equal to twice thethickness of valvedisk I53. Port I6'I communicates by way of passage I10(see Fig. 6) with the aforementioned pipe 'II leading to workingcylinder I6, while port I68 communicates by way of passage I'II withpipe connecting with the interior of accumulator I5. Immediatelyadjacent and to the outside of ports I61 and I68 are valve seats I'I4and I15, of the same dimensions as valve seats I65 and I66.

Surrounding valve bore I 40 immediately adjacent and to the outside ofvalve seats I14 and I75 are annular ports I16 and III, of dimensions,measured axially of the valve bore, again equal to twice the thicknessof valve disk I53.

Port I16 is in open communication with pump discharge passageway I63,whileport I'll is in open communication with pump discharge was sagewayI68, as shown in Fig. 2. The master valve is so proportioned that whenvalve element I53 is, for instance, seated on its seat I66, as in fulllines in Fig. 2, piston section or element I50 will be outside of portIll, establishing free communication between pump discharge passagewayI64 and port I68 leading to tank 25, whereas piston section or elementII will at this time be seated on valve seat I78 and will therefore forma barrier between pump discharge passageway I63 and port I6I leading tothe working cylinder. In the particular form of valve here illustrated,and with the proportions of valve seat and liquid port dimensions asgiven above, these relations are obtained by making the spacing betweenthe valve disk I53 and each one of the pistonheads I50 and I5Isubstantially equal to five times the thickness of the central disk I53.With the valve in the full line position of Fig. 2, the outer end ofpiston section I50 is in engagement with the abutment presented by theopposed face I80 of end casting I 32, as shown in Fig. 2. Valve disk I53being seated on valve seat I66, suction chamber |6I of the pump is thenin open communication with port I61 leading from working cylinder I6, sothat liquid will be pumped from the working cylinder via pipe II, portsI61 and I60, suction chamber 'I6I, dis charge passageway I68, ports Illand I68, and pipe 80 to tank I5, permitting the piston and pump stringto descend.

It will be understood that when the master valve is in its extremeposition toward the left, valve element I53 will be seated on seat I55,valve element I5I will be to the left'of port I78 and in engagement withthe abutment presented by the opposed face IIlI of end casting I lI,with valve element I50 seated on valve seat H5. Under such conditions,liquid will be pumped from tank I5 via pipe 80, ports I68 and iBD (thenin open communication), pump suction chamber IBI, pump dischargepassageway I88, ports I78 and I6! (then in open communication) and pipeII to working cylinder I6 to elevate piston and the pump rod string.

A feature of the invention in one of its primary aspects involvesoperation of master valve II5 under the differential pressure of fluidsat two different pressure levels. In accordance with the presentpreferred form of the invention, the high pressure fluid sourceconstitutes the aforementioned high pressure tank, which contains oilunder a pressure substantially above that in main tank I5, while thelower pressure is supplied from any suitable low pressure point in theoil circulation system. While this feature is not indispensable tocertain other aspects of the invention, and is therefore not specifiedin all of my claims, it leads to certain very important advantages andresults, especially in conjunction with the other aspects of the'invention, as will presently appear, and incorporation of this featureis therefore deemed preferable and important. For control of this highpressure valve-operating fluid, a four-way pilot valve is preferablyemployed, and while this pilot valve may be embodied in variousmechanical forms, and may or may not be incorporated within the body ofthe pump unit I1, I prefer to employ a balanced pilot valve working in apilot valve bore I in end casting I4I. This preferred pilot valve, whichis designated generally by numeral I88, comprises two rod or pistonsections I81 and I88, a connecting valve rod I89 of reduced crosssection, and a central valve disk or element I90 mounted on rod I89midway between piston sections I81 and I88. Pilot valve i86 is adaptedto be mechanically moved by means of a link I9I pivotally connected tothe outer end or piston section I81 and operated in accordance with thereciprocation of working piston 80, in a manner later to be explained.Section I8! is packed by means of a suitable gland at I93, and sectionI88 is packed by similar gland'at I94. A series of five equally spacedannular ports I through I99 surround valve bore I85, the spacing betweensaid ports being substantially equal to the length dimension of valveelement I90, and the wall portions of bore I85 between central port I97and the adjacent ports I86 and I98 providing annular seats ISM and IBM,respectively, for valve element I90.

It is preferable and convenient, and a feature of the present invention,that the high pressure fiuid utilized to operate master valve II5 besupplied or kept up from the discharge side of pump P. For this purpose,a high pressure line 200 is connected into pump discharge passageway i83(Fig. 2), and this high pressure line 200 is connected to the previouslymentioned line-89 leading to small high pressure tank 88, and also to apassageway 28I leading to the aforementioned port, 496 (Fig. 3). A checkvalve 208 in line 280 between the pump and the connection with line 39holds the pressure in, tank 88 when the pump is stopped. Z'Ihe dischargeside of pump P as well as tank 88 are thus in communication with pilotvalve passageway 20I and port I98. It has previously been mentioned thata certain air pressure, as for example 50 lbs. pressure in excess of thepressure in tank I5, is preferably initially built up in tank 88 bymeans of compressor 20. The pump P, which during a part of the operatingcycle delivers liquid at a pressure equal to (R+C) discharges liquid vialine 258 and 88 to tank 88, the pressure in which is thus kept up toapproximately (R+C).

Annular port I95 (Fig. 3) communicates via passage 205 with a dischargepipe line 20'! that preferably discharges to a low pressure point in theworking liquid system. By thus discharging the valve operating liquidback to the working liquid system, the necessity for frequentreplenishing of the working liquid is avoided. As here shown, this line201 is connected to a port 201a opening inside pump intake chamber I6I.An alternative arrangement, indicated in Figs. 1 and 11 in dotted lines,consists of a line 201' discharging back to tank I5.

Central valve bore port I91 communicates via passageway 2I0 in endcasting I4I with one end of a passageway ZII extending longitudinallythrough valve chest M5, the other end of the latter communicating with apassageway 2I2 in end casting I42. Passageway 2I2 communicates in turnwith a vertical, check-valved passageway 2I3, from which leads ahorizontal port 2M opening through surface I80 of the end casting andcommunicating with the liquid chamber at the right-hand end of mastervalve bore 140, as viewed in Fig. 2. This liquid chamher will beobserved to be defined by wall surface I80, the end portion of valvebore I40, and to be closed by the pressure area on the end of mastervalve piston section I50.

The two end or outside valve bore ports I95 and I99 (Fig. 3) communicatevia passageways 220 and 22I, respectively, with a passageway 222 (seeFigs. 6 and 4), and the latter communicates with a vertical,check-valved passageway 223, from which leads a horizontal port 224opening through surface i8I of end casting MI and communicating with theliquid chamber at the left-hand end of master valve bore M0, this liquidchamber being defined by wall surface I8I, the end portion of valve boreI40, and being closed by the pressure area on the end of master valvepiston section Ii.

The check-valved passageways 2I3 and 223 and the adjustable check valveelements contained therein are similar and a detailed description of onewill suffice for both. Referring particularly to Figs. 2, 5 and 6, itwill be seen that passageway 2 I3 consists of a vertical bore 225extending downwardly from the upper end of end casting I42 to a pointsomewhat short of passageway 2I2, and a reduced bore 226 continuingdownwardly from bore 225 through to passageway 2I2, the constructionproviding an upwardly facing annular stop shoulder 227 for the checkvalve element, designated by numeral 228. As shown, bore 225 is enlargedsomewhat at its lower end, just above shoulder 22?, for example asindicated at 229. and is formed with an enlargement at 230 at itsjunction with horizontal port 2M.

The check valve 228. in the typical form here shown, comprises acylindrical body 23I formed with a plurality of longitudinally extendingribs 232 slidably fitting bore 225. The upper end of bore 225 is closedby means of a plug 233 screwed into an internally threaded socket 232formed at its upper end.

Check valve 228 when in its lower position rests on the upper end of anadjustment member, here shown in the form of a vertical rod 235adjustably mounted in casting I62, so as to provide a restrictedclearance space between its lower end and shoulder 22? (see the dottedline position in Fig. 5). As here typically shown this rod 235 has ascrewthreaded section 233 threaded within casting I42 and extendingthrough the lower side thereof, having on its lower end a head 231 bymeans of which it may be turned. A look nut 238 may be employed totighten member 235 in adjusted position.

As previously mentioned, passageway 223 in end casting I4I may beidentical with that just described, being provided with a check valve228 and check valve adjustment member 235 exact- 1y as described inconnection with liquid passage H3 in end casting I42.

When liquid flows upwardly via passage 2I2 and engages the lower side ofcheck valve 228, it lifts the latter as to the position illustrated inFigs. 2 and 5, permitting free flow of fluid through passageway 2I3 tohorizontal port 2M leading to the right hand end of master valve bore I40. Similarly, upward flow of liquid against the check valve 228 in endcasting IiI will elevate that check valve in a like manner to permitfree flow of fiuid via passageway 223 and port 224 into the left handend of master valve bore I40. Cheek valves 228 normally assume theirlowermost positions, in engagement with the upper ends of supportingrods 235. In such 76 positions downward flow of fiuid therepast ischecked or restricted, downward flow taking place through the spacesbetween check valve ribs 232 to the reduced portion 226 of the checkvalved passageway. The restriction effected by the check valve dependsfinally upon the elevation of the check valve above annular shoulder227, so that downward flow through these passageways is easilyadjustable simply by adjustment, of rods 235. The purpose of thisadjustment will be more fully explained at a later point in thespecification.

Opening within master valve bore I40 are two ports 24!] and MI (Fig. 6),which are adapted to be controlled by piston sections I50 and I5I,respectively, of master valve II5. Port 240 leads to the aforementionedpassageway 2II, while port 24! leads to a fluid passageway 242 thatcommunicates with a fluid passageway 243 leading through end casting MIto the aforementioned passage 222. Port 24I is so located that it iscompletely covered by piston section I5I of master valve II5 when thelatter has moved toward the left (as viewed in Figs. 2 and 6) from itsextreme right-hand position a distance sufficient that valve elements653 and 'I5I are just ready to crack or separate from valve seats I66and H4, respectively, this position being shown in full lines in Fig. 6.In a similar manner, port 242 is so located that it is completely closedby piston section I50 of valve II5 when said valve has moved from itsextreme left-hand position a distance toward the right sufiieicnt tobring valve elements I50 and I53 to the point of cracking from seats il5and I65, respectively.

Pilot valve I86 is movable between the position shown in Fig. 3,'inwhich its central valve element W0 is seated on valve seat IBM, and aposition shifted toward the left, as viewed in said figure, in whichvalve element I90 is'seated on valve seat I96a. As previously indicated,this pilot valve is operated by the working piston, means being providedfor shifting the pilot valve just as the piston reaches or approachesthe desired limiting positions of its stroke. Figs. 1 and 9 show atypical and present preferred linkage for accomplishing this result,though it will .be understood that any other found simple or appropriatemay be substituted if desired. As shown in Fig. 9, a vertical cammingbar 256 is mounted on the upper end of piston 48 by means of a bracketarm 25!, bar 250 extending downwardly alongside the cylinder. Bar 250 isreceived in a way 252 extending downwardly along the side of cylinderhead 27 and through cover member 58 and ring 30. This bar 250 isconfined within way 252 by a keeper plate 253 secured to the side ofcylinder head 27 and overlying way 252. Upper and lower cam elements orplates 254 and 255 are secured to the outer face of bar 250, beingmounted at opposite edges of said bar so as to be horizontally offsetfrom one another (see Fig. 1). The inner side of keeper plate 253 isnotched, as indicated in Fig. 9b, to accommodate cam elements 254 and255. These cam elements 254 and 255 are provided with straight verticaledges 254a and 2550., respectively, and with tapered ends 2541) and2551), re-

spectively, the tapered portions being on the lower end of upper camelement 254 and on the upper endof lower cam element 255.

These cam elements 254 and 255 engage follower rollers 256 and 257,respectively, rotatably mounted on the ends of the two arms of a bellcrank 258, the latter being rigidly mounted on a.

stub shaft 259 journaled in brackets 260 secured to the side of cylinderhead 21. Tightly mounted on stub shaft 259 and extended horizontallytherefrom is a swinging arm which is connected by a vertical link 262with one arm of a bell crank 253 pivotally mounted at 255 on fitting 26.The other arm of bell crank 203 is connected by the aforementioned linkI9I to the pilot valve, as previously mentioned. The two rollers 256 and251 borne by the two arms of bell crank 258 are on opposite sides ofsaid arms and are in alinement with cam elements 255 and 255, in suchmanner that roller 255 will be exclusively engaged and operated by camelement 250 and roller 251 will be exclusively engaged and operated bycam element 255.

Fig. 9 shows piston 20 near the bottom limit of its stroke, and it willbe understood that follower roller 255 has ridden up the incline of thetapered portion 2502) of upper cam element 250, causing bell crank 258to swing in a counterclockwise direction, thereby moving link 252 in adownward direction and swinging bell crank 263 in a counter-clockwisedirection, which results in moving link I9I in a direction to shiftpilot valve I86 to the position illustrated in Fig. 3. Bell crank 258having swung to the position illustrated in Fig. 9, cam bar 250 ma movedownwardly somewhat further before reversal occurs, roller 250 at thistime riding on vertical edge 254a of cam element 255 and roller 251riding on the vertical surface of bar 250, as Will be clear frominspection of Fig. 9.

As the piston reverses direction and travels through its up stroke bellcrank 258 remains in the position illustrated in Fig. 9, roller 251continuing to rise on the surface of bar 250, and roller 256 maintainingits separation from bar 250 notwithstandingthe fact that it is no longersupported in such position by cam element 255. In other words, duringthe up stroke the pilot valve operating linkage remain in the positionof Figs. 1 and 9, friction in the various connections holding thelinkage against displacement.

As the upper end of the strok is approached, the inclined surfac 2551701 lower cam element 255 engages lower follower roller 's and causes itto swing out, bell crank 258 moving in a clockwise direction untilroller 255 i in engagement with the surface of bar 250, this causing thepilot valve linkage to withdraw pilot valve I86 to a position withcentral valve element 90 on seat I96a, between port I95 and I91. Thepilot valve linkage then remains in this position until, near the bottomof the down stroke, it is operated by cam element 254 to swing again tothe position of Fig. 9,

The complete cycle of operations of the system may now be described.Assume that piston is approaching the lower limit of its down stroke(Figs. 1 and 9), and that the pilot valve I86 has been moved to theposition illustrated in Fig. 3. Master valve I15 will have been in itsextreme right-hand position, as viewed in Fig. 2, and liquid will havebeen flowing from cylinder I6 by way of pipe H and the valve and pumpsystem to tank I5 as follows: pipe 1|, valve port I61, valve port I60,pump suction chamber I5I, pump discharge passageway I65, valve port I11,valve port I58, and pipe 80 to tank I5. The pressure in the cylinder atthis time is substantially that necessary to counterbalance the pump rodstring,

or just less than counterbalancing pressure, and

the pump is raising the pressure of the liquid from that pressure totank pressure.

The described shift of pilot valve I85 to the position of Fig. 3 as thelower limit of th piston stroke is approached allows high pressureliquid to flow from high pressure line 200, see Fig. 3, via passageway20I, valve port I96, port I91, passageways 2I0, 2II, 2l2 (Fig. 5)passageway 2I3 (check valve 228 becoming elevated to the position ofFig. 5 by the pressure of the liquid), and port 2%, to be discharged-tovalve bore I40 to act against the outer end of piston section I of themaster valve. a

This high pressure liquid, at a pressur of approximately (R-l-C), actingagainst the outer end of the piston section I50 of the master valve, isopposed by liquid at a lower pressure, for example, the pressure at theintake side of the pump, acting against the outer end Of the pistonsection I5I at the other end of the master valve. The master valveaccordingly travels toward the left, the liquid ahead of piston sectionI5I being expelled as will presently be traced.

The sequence of operations and conditions passed through during suchmovement of the master valve from right to left is as follows: Theliquid in piston bore 30 ahead of piston section I5I is expelled by wayof port 220 and checkvalved passageway 223 to passageway 222, and also,during the first portion of the stroke of the master valve, by way ofport 201 and passageway 202 and 243 to passageway 222. From passageway222 this liquid flows by way of passageway 22I (Fig. 6) into valve portI99, and from there flows to valve port I98, from which it is dischargedby way of passageway 206 to pipe line 201 leading to the intake side ofthe pump.

Check valve 228 in passage 223 being at this time,

in its lowermost position, resting on rod 235, outflow of liquid by wayof port 220 and passageway 223 is considerably restricted. Out-flow byway of port 2 H, however, is comparatively free, port 2 H being of suchdiameter as will permit the liquid to be rapidly expelled until it iscovered by the piston section 651 of the master valve. This occurs, aspreviously described, when the master valve has moved toward the left adistance sufficient that cracking of valve elements I53 and I5I fromseats M5 and I15 is imminent (Fig. 6). The travel of the master valvefrom the position of Fig. 2 to the position of Fig. 6 has not restrictedthe free llow of liquid from port I61 through port I to suction chamberI5I, nor the flow of liquid from exhaust passageway I54 via port I11into port I08 leading to the tank. The only efiect of the travel of themaster valve from the position of Fig. 2 to the position of Fig. 6 is,therefore, to close port 2% and restrict all further discharge of liquidfrom ahead of piston section i5I to port 225 and check valve passageways223, thereby reducing the speed of travel of the master valve to adetermined rate depending upon the adjustment of check valve 228.

Further travel of the master valve toward the left then causesseparation of valve element I53 from seat I06, separation of pistonsection I5I from seat I10, and an approach of piston section I50 towardseat I15, with the following results: Liquid from pump dischargepassageway I60 begins to travel past valve element 53 directly to pumpsuction chamber I6I, and at the same time liquid begins to flow frompump discharge passageway I53 past piston section I5I to port I15 andthence via port I50 to pump suction chamber ifiI. Tank I5 is incommunication with pump intake chamber l6I via a gradually wideningpassageway, and the pressure in pump suction (If-kg) The pressure inpump discharge passages I63 and I64 correspondingly increases from theoriginal value of toward a value of (R+C), the pump operating to raisethe head of the liquid by an amount equal to ml Q The flow of liquid tothe tank becomes less and less, both because of the increasingrestriction between piston section I50 and valve seat I15, and becauseof the by-pass of an increasing quantity of liquid from port I68directly back to suction chamber I6I. At the same time, the flow ofliquid from the cylinder becomes less and less, by reason of increasingflow of the high pressure liquid from pump discharge passageway I63 toport I61, and increasing restriction of the flow from port I61 to portI60 and suction chamber I6I due to approach of valve element I53 towardseat I65.

By the time the master valve has reached its central position (Fig. 2 indotted lines), flow from the cylinder toward the pump and from the pumptoward the tank has stopped, and downward travel of the working pistonand upper end of the pump rod string has ceased, though the lower end ofthe string may continue downwardly for a short time due to inertiaforces stretching the pump string. The total of the liquid flowing fromdischarge passageways I63 and I64 into ports I61 and I68 at this timegoes past valve seats I65 and I66 to port I60 and pump suction chamberI6I, and no liquid is taken in from pipe II connecting with the cylindernor being discharged through pipe 80 to the tank. At this time thepressures in tank I5 and in the cylinder are substantially equalized andthe pump is merely circulating liquid locally.

As the master valve then continues to travel further toward the left, i.e., from the position indicated in dotted lines in Fig. 2 toward theposition in which valve element I53 just closes the passageway betweenports I61 and I60 and in which piston section I50 just closes thepassageway between ports Ill and I68, the following occurs: Because ofthe approach of piston section I50 toward valve seat I75, fiow from pumpdischarge passage I64 is gradually reduced to zero, while at the sametime movement of valve element I53 away from seat I66 and toward seatI65 initiates a flow from port I 63 toward suction chamber I6I andgradually decreases the flow from port I61 toward said suction chamberto zero. At the same time, further recession of piston section I5I fromseat I14 is gradually increasing flow from pump discharge passage I63 toport I 67. It follows that as the master valve travels toward the leftfrom its central position (dotted lines in Fig. 2), liquid begins toflow from the tank via ports I68 and I60 to pump suction chamber I6I,and liquid begins to be pumped toward the cylinder by way of dischargepassage I63 and port I67. The pressure of the liquid in the cylinder isnot yet up to (R+C), such as is required to lift the entire pump stringand column of well fluid, but the liquid being pumped toward and intothe cylinder at this time is increasing toward that value and is undersufficient pressure to begin slowly to lift the working piston and rodstring, which have not yet assumed the fluid column load. As a matter offact, it may 'occur that the working piston will already have begun aslow upward movement, due to increase in pressure of the liquid withinthe cylinder because of opening of communication between the cylinderand tank, and this may be especially noticeable when the tank isoperating under an overcharge of pressure. In the course of the travelof the master valve toward the position in which valve elements I53 andI50 just reach seats I65 and I15, respectively, the lower end of the rodstring termintes its downward travel and begins to elevate by reason ofresilient contraction, causing the travelling valve to close. Furtherupward travel of the working piston under the gradually increasingpressure in the cylinder then stretches out the rod string, until thefull load of the rod string plus the weight of the fluid column is onthe piston. By this time valve element I53 is on its seat I65, flow frompassage I64 is interrupted by piston section I50, pump intake chamberI6I is in unrestricted comunication with tank I4, and pump dischargepassageway I63 is in unrestricted communication with the workingcylinder and therefore supplies liquid to the cylinder at full highpressure (R-i-C), so that the piston then elevates the entire rod stringand column of well fluid. The speed of this travel of course dependsupon the speed at which driving pump P is operated.

As previously noted, the master valve moves comparatively quickly fromits extreme righthand position to the position of Fig. 6, where outletport 2M is closed, at which point its speed is reduced as determined bythe setting of check valve adjustment member 235. The time within whichthe deceleration and acceleration of the working piston and upper end ofthe pump string must occur depends upon this reduced speed of travel ofthe master valve, and hence upon the setting of the controlling checkvalve, which may thus be readily set to provide a smooth and easydeceleration, and an acceleration which is timed with the rebound of thepump string, the action being such that the stretch is substantially outof the rod string and the travelling valve is closed when the fulloutput pressure of the circulation pump is applied to the piston and thepiston and rod string are accordingly up to maximum speed. The timingthus made possible is conducive to smoothest and most efficientperformance, and to the elimination of undesirable whipping of the rodstring as the load of the well fluid is assumed.

Master valve H5 having been moved to its extreme left-hand position,liquid will be taken from tank I5 and delivered to the cylinder toelevate the working piston and pump rod string, as mentioned above. Nearthe upper end of the stroke, cam element 255 of car bar 250 strikesfollower roller 25? and swings bell crank 258 in a clockwise direction,thereby operating the pilot valve linkage to move pilot valve I86 in alefthand direction, as viewed in Fig. 3. at which time valve element I90is seated on seat I96a, valve port I99 is closed by piston section I88.valve port I98 is in communication with valve port I91, and valve portI96 is in communication with valve port I95. At this time, high pressureliquid flows by way of high pressure lin 200 and passageway 26I to valveport I96, from there to from scat I65.

port I95, and thence via passageways 220 (see Fig. 6) 222, 223, and 224to be discharged against the end of piston section II of master valveH5. It will be understood that such passage or high pressure liquidupwardly through passageway 223 will elevate the corresponding checkvalve 228 to provide a free passageway for how of high pressure liquidto and against piston section I5I. At the same time. liquid ahead ofpiston section I50 is cxpclled by way of port 2M. passageway 2 I3 (thenrestricted by its check valve 228, which is at such time in itslowermost position) thence flowing by way of passageways 2I2, 2| I,2I0,' port I91, past seat I98a (from which valve element I90 is at thistime removed), to port I98 leading via passage 206 to pipe line 201discharging to the intake side of pump P. 2

Liquid also flows from ahead of piston section I50, during the initialportion of the stroke of the master valve toward the right, by way ofport 240 discharging directly into passageway 2I I. v

When the master valve has moved sumciently toward the right thatcracking of valve elements I53 and I50 from seats I65 and I is imminent,port 240 is just closed by piston section I50, so that the master valveis checked in speed and the remainder of its travel toward the rightreduced to a rate permitted by the degree of restriction of passageway2I'3 by its check valve element 228. As before, no change in operation,other than reduction in speed of travel of the master valve. is eifectedby the initial travel of the master valve prior to cracking of valveelement I53 As valve element I53 separates from seat I65 and pistonsection I50 separates from scat I15, however, liquid from pump dis'charge passageway I63 begins to travel past valve clement I53 directlyback to pump suction chamber IBI, and liquid begins to flow from pumpdischarge passageway I64 past piston section I50 to port I08 and thencevia port I50 to pump suction chamber I6I. The flow of liquid to thecylinder becomes less and less, both because of increasing restrictionbetween piston section I5I and valve seat I14, and because of theby-pass of an increasing quantity of liquid from port I61 past valveseat I65 to pump intake chamber I6I. At the same time, the flow ofliquid from the tank toward the pump becomes less and less, by reason ofincreasing flow of liquid from pump discharge passageway I64 to portI68, and decreasing flow from post I68 via port I60 to suction chamberIBI due to the approach of valve element I53 toward seat I66. Travel ofvalve element I53 toward the right within port I60 gradually restrictsthe passageway from the tank past seat I66 and through port I60 to thepump intake chamber, while at the same time increasing the size of thepassageway between port I61 and pump suction chamber I6I', this havingthe effect of gradually reducing the intake pressure existing withinchamber I6I from to R during the course of travel of piston element I53to the full line position of Fig. 6, the discharge pressure of the pumpfalling correspondingly to a value of By the time the master valve hasreached its central position (dotted lines in Fig, 2) flow from the tankand toward the cylinder has stopped, and upward travel of the workingpiston and the upper end of the pump rod has ceased. The travellingvalve of the well pump will still be closed, and because of thecommunication now established between the cylinder and tank, thepressure in the cylinder will fall below pressure (R+C), whereupon-thepiston and upper end of the rod string will begin slowly to descend. Thetotal ofv the liquid flowing from discharge passageways I63 and I64 intoports I61 and I68 at this time goes past valve seats I65 and I66 to portI60 andpump intake chamber I6I. and no liquid is taken in from pipeconnecting with the tank nor discharge through pipe 'II to the cylinder.

As the master valve then continues to travel further toward the right,i. e., from the position indicated in dotted lines in Fig. 2 toward theposition shown in full lines in Fig. 6, liquid is drawn from thecylinder at a gradually increasing rate and liquid is pumped toward thetank at a correspondingly increasing rate. The downward travel ofworking piston thus accelerates, the rate of acceleration being governedby the speed of travel of the master valve, which is regulated aspreviously explained. After the master valve position of Fig. 6 isreached, liquid is pumped from the cylinder toward the tank at normaloperating speed (depending upon the speed of operation of the pump), thepiston and pump string then descending at maximum speed. The lowering ofthe pump string causes the travelling valve to open, after which pump Ptakes liquid from the working. cylinder, raises it to the pressure oftank I5, and delivers it to the tank. v

A novel and important feature of my pump and valve system is that duringreversal of the direction of pumping stroke, the working cylinder is inconstant communication with the tank, so that the usual jarring andwater hammer occasioned by complete cut-off of the line to the workingcylinder is entirely eliminated and instead the piston in the workingcylinder is constantly cushioned by the air pressure in tank I5.Attention is particularly directed to the novel action of the pump andmaster valve during reversal of the direction of flow between tank andcylinder. As the master valve moves, it gradually decreases fiow, e. g.,from the pump through the valve chamber to the cylinder, and graduallycorrespondingly decreases flow from the tank through the valve chamberto the pump. At the same time, a local ring circulation from the pumpthrough the valve chamber and back to the pump is initiated, whichincreases until the entire output of the pump is diverted in thismanner, Further travel of the master valve then causes liquid to bediverted from this local ringcirculation and delivered to the tank, andat the same time causes the pump to begin to take liquid from thecylinder. In this phase of the cycle the master valve graduallydecreases the local ring circulation to zero, and gradually increasesthe circulation from the cylinder to the pump and from the pump to thetank to maximum. There is thus a gradual transition from maximum flow inone direction to maximum flow in the other, without ever closing offcommunication between tank and cylinder, the pump circulating liquidlocally through the valve during the transition, and all of the liquiddischarge by the pump taking part in this local ring circulation throughthe valve at the time flow between tank and cylinder momentarily ceasespreparatory to reversing its direction.

One of the primary features of the invention is the provision of meansfor regulating the ratesof deceleration and acceleration of the workingpiston, independently. of its speed of travel between the deceleration.and acceleration zones. This enables adjustment of the acceleration anddeceleration to rates best suited to any given pump rod string, as wellas permitting operation at a comparatively high linear pumping speed.

And an outstanding feature of advantage in the pumping system of theinvention is the use of a novel, simple and effective fluid pressuremeans for operation of the main or master valve, this fluid pressurevalve operating means avoiding all dead center problems and complicatedand unsatisfactory mechanical expedients for throwing the main valvepast dead center position, as inevitably encountered in purelymechanical valve operating mechanisms.

I have now described a present preferred embodiment of my invention inconsiderable detail; it will be understood, however, that this is forillustrative purposes only, and so that the principles inherent in myinvention will be fully un derstood, the invention being susceptibletovarious changes in design, structure and arrangement without departingfrom the spirit and scope of the invention or of the appended claims.

I claim:

1. A reversible flow pump and valve unit, comprising a housing, a pairof meshing gear type pump rotors rotatably mounted in said housing onparallel axes, a pair of arcuate walls in said housing positionedclosely adjacent opposite sides of said pair of pump rotors,corresponding end edges of said arcuate walls being spaced apart topermit liquid fiow therebetween, a valve bore in said housing positionedto one side of said pair of pump rotors and extending in a directionsubstantially transversely of said rotor axes, a series of five axiallyspaced annular ports around and communicating with said valve bore,walls in said housing establishing direct communication between thecentral one of said annular ports and a space at the adjacent side ofthe two pump rotors between the two adjacent end edges of said arcuatewalls, said housing including walls which, together with the outersurface of said arcuate walls, define two passageways extending betweena space at the opposite side of the two pump rotors, between the twoadjacent end edges of said two arcuate walls, around the outer sides ofsaid two arcuate walls, and communicating with the two outside annularports, passageways extending inside said housing and communieating withthe two annular ports between said middle and outside ports, and a valvereciprocable in said valve bore between two positions and adapted toestablish communication between the central annular port and one of theannular ports next outside and communication between the other annularport next outside and the adjacent outside annular port when in one ofsaid positions, and communication between the central annular port andthe other of the annular ports next outside and communication betweenthe other annular port next outside and the adjacent outside annularport when in the other of said positions.

2, A reversible flow pump and valve unit, comprising a housing, a pairof meshing gear type pump rotors rotatably mounted in said housing onparallel axes, a pair of arcuate walls in said housing positionedclosely adjacent opposite sides of said pair of pump rotors,corresponding end edges of said arcuate walls being spaced apart topermit liquid flow therebetween, walls closely spaced to the ends ofsaid pump rotors and completing the enclosure of said pump rotors exceptfor the spaces between said end edges of said arcuate Walls, a valvebore in said housing positioned to one side of said pair of pump rotorsand extending in a direction substantially transversely of said rotoraxes, a series of five axially spaced annular'ports around andcommunicating with said valve bore, walls in said housing establishingdirect communication between the central one of said annular ports and aspace at the adjacent side of the two pump rotors between the twoadjacent end edges of said arcuate walls, said housing including wallswhich, together with the outer surface of said arcuate walls, define twopassageways extending between a space at the opposite side of the twopump rotors, between the two adjacent end edges of said two arcuatewalls, around the outer sides of said two arcuate walls, andcommunicating with the two outside annular ports, passageways extendinginside said housing and communicating with the two annular ports betweesaid middle and outside ports, and a valve reciprocable in said valvebore between two positions and adapted to establish communicationbetween the central annular port and one of the annular ports nextoutside and communication between the other annular port next outsideand the adjacent outside annular port when in one of said positions, andcommunication between the central annular port and the other of theannular ports next outside andcommunication between the other annularport next outside and the adjacent outside annular port when in theother of said positions.

3. A reversible flow pump and valve unit, comprising a housing, a pumpembodying a pair of interacting pump rotors rotatably mounted in saidhousing on parallel axes, at pair of arcuate walls in said housingpositioned closely adjacent opposite sides of said pair of pump rotors,corre sponding ends of said arcuate walls being spaced apart to permitliquid flow therebetween, a valve bore in said housing positioned to oneside of said rotors, a series of five axially spaced ports openingwithin said valve bore, a passageway in said housing establishingcommunication between the central one of said ports and the liquid flowspace between corresponding ends of said two arcuate walls, passagewaysin said housing extending from the liquid flow space between the othercorresponding ends of said two arcuate walls around the outer sides ofsaid two arcuate walls and communicating with the two outside ports,external liquid connections with the two ports between said central andoutside ports, and a valve reciprocable in said valve bore between twopositions and adapted to establish communication between the centralport and one of the ports next outside and communication between theother port next outside and the adjacent outside port when in one ofsaid positions, and communication between the central port and the otherof the ports next outside and communication between the other port nextoutside and the adjacent outside port when in the other of saidpositions.

4. A reversible flow prising a housing, interacting pump pump and valveunit, coma pump embodying a pair of rotors rotatably mounted in saidhousing on parallel axes, a pair of arcuate walls in said housingpositioned closely adjacent opposite sides of said pair of pump rotors,corresponding ends of said arcuate walls being spaced apart to permitliquid flow therebetween, a valve bore in said housing positioned to oneside of said pair of pump rotors and extending in a directionsubstantially transversely of the rotor axes, a series of five axiallyspaced ports opening with in said valve bore, a passageway in saidhousing establishing communication between the central one of said portsand the liquid flow space between corresponding ends of said two arcuatewalls, passageways in said housing extending fromthe liquid flow spacebetween the other corresponding ends of said two arcuate walls aroundthe outer sides of said two arcuate walls and communicating with the twooutside ports, external liquid connections with the two ports betweensaid central and outside ports, and a valve reciprocable in said valvebore between two positions and adapted to establish communicationbetween the central port and one of the ports next outside andcommunication between the other port next outside and the adjacentoutside port when in one of said positions, and communication betweenthe central port and the other of the ports nextoutslde andcommunication between the other port next outside and the adjacentoutside port when in the other of said positions.

5. A reversible flow pump and valve unit, comprising a housing, pumprotor means in said housing, curved walls in said housing defining theperiphery of a rotor chamber for said rotor means, spaced end walls insaid housing closing the ends of said rotor chamber, liquid intake anddischarge ports communicating with said rotor chamber, a valve bore insaid housing positioned to one side of said pump rotor means, a seriesof five axially spaced ports opening inside said valve bore, a liquidpassageway in said housing extending around the outside of said curvedrotor chamber walls and establishing communication between one of saidrotor chamber liquid ports and the two outside valve bore ports, aliquid passageway in said housing establishing communication between theother of said rotor chamber liquid ports and the central one of thevalve bore ports, external liquid connections with two valve bore portsbetween said central and outside ports, and a valve reciprocable in saidvalve bore between two positions and adapted to establish communicationbetween the central port and one of the ports next outside andcommunication between the other port next outside and the adjacentoutside port when in one of said positions, and communication betweenthe central port and the other of the ports next outside andcommunication between the other port next outside and the adjacentoutside port when in the other of said positions.

6. A reversible flow pump and valve unit, comprising a housing, pumprotor means in said housing, curved walls in said housing defining theperiphery of a rotor chamber for said rotor means, spaced end walls insaid housing closing the ends of said rotor chamber, liquid intake anddischarge ports communicating with said rotor chamber, a valve bore insaid housing positioned to one side of said pump rotor means andextending substantially transversely thereof, a series of five axiallyspaced ports opening inside said valve bore, a liquid passageway in saidhousing extending around the outside oi'said curved rotor chamber wallsand establishing communication between one of said rotor chamber liquidports and the two outside valve bore ports, a liquid passageway in saidhousing establishing communication between the other of said rotorchamber liquid ports and the central one oi the valve bore ports,external liquid connections with two valve bore ports between saidcentral and outside ports, and a valve reciprocable in said valve borebetween two positions and adapted to establish communication between thecentral port and one of the ports next outside and communication betweenthe other port next outside and the adjacent outside port when in one ofsaid positions, and communication between the central port and the otherof the ports next outside and communication between the other port nextoutside and the adjacent outside port when in the other of saidpositions.

'7. A reversible flow pump and valve unit, comprising a housing, a pumpembodying a pair of interacting pump rotors rotatably mounted in saidhousing on parallel axes, a pair of arcuate walls in said housingpositioned closely adjacent opposite sides of said pair of pump rotors,a valve bore in said housing positioned to one side of said rotors, aseries of five axially spaced ports opening within said valve bore, apassageway in said housing establishing communication between thecentral one of said ports and one side of said pair of interacting pumprotors, passageways in said housing around the outer sides of saidarcuate walls and communicating at their one ends with the other side ofsaid pair of interacting pump rotors, and'at their other ends with thetwo outside ports. external liquid connections with the two portsbetween said central and outside ports, and a valve reciprocable in saidvalve bore between two positions and adapted to establish communicationbetween the central port and one of the ports next outside andcommunication between the other port next outside and the adjacentoutside port when in one of said positions, and communication betweenthe central port and the other of the ports next outside andcommunication between the other port next outside and the adjacentoutside port when in the other of said positions.

JOHN A. VERTSON.

